1. Field of the Invention
The present invention relates to a supplemental sub-operation for cargo container handling by gantry cranes for improving the efficiency of the container handling cycle time. More particularly, it relates to a new method of operation for dockside quay cranes. Specifically, it relates to the supplemental operation of a buffer crane which functions in conjunction with cargo container handling gantry cranes.
2. Description of the Prior Art
The utilization of various types of cargo container handling gantry cranes or quay cranes for the purpose of increasing the speed of loading and unloading of cargo container transport ships is well-established in the prior art. However, despite the numerous designs, structures, and methods of operation disclosed by the prior art, which have been developed for the accomplishment of the specific objectives, purposes, and requirements of cargo container handling, the apparatus and methods which have heretofore been devised and utilized consist basically of familiar, expected, and obvious configurations, combinations, and arrangements of well-known machinery operations. This will become apparent from the following consideration of the closest known and relevant prior art.
Shipping companies wish to reduce the time a ship spends in port involved in berthing operations in order to increase the efficiency of each vessel. Increasing the productivity of berthing operations allows ships to be loaded and unloaded faster, thereby effectively reducing the ship""s down time. Efforts are continuously being made to further this objective. The present invention is a significant advancement in these efforts.
Reference is made to FIG. 1 of the drawings which shows a typical dockside berthing operation for a ship. The primary container handling equipment is comprised of one or more quay cranes 11 which extend outboard from the dock""s edge 13 across the beam of a ship 15. Cargo containers 17 which have been unloaded or are to be loaded are temporarily stored in a stacking yard 19 proximate to the ship""s loading berths. The berthing operations under specific consideration involve the transport of containers between a container ship and the stacking yard.
In ship unloading operations, quay cranes 11 access the shipboard cargo containers from above the ship and move them to the ground level or dockside cargo container transporters 21 such as chassis trucks, trailer trucks, or automatically guided vehicles (AGVs). The transporters deliver the containers to the stacking yard 19 where other vehicles or cranes 23 transfer the containers to stacks. In loading operations, quay cranes lift the cargo containers from the dockside container transporters and move them to the ship where they are lowered into shipboard cells. The berthing operations involve three separate types of sub-operations: (1) quay crane handling; (2) transport between the crane and the stacking yard; and (3) storage yard manipulation.
Quay cranes in the form of cargo container handling gantry cranes are arranged to extend over a longitudinal expanse and transfer cargo containers horizontally from one deposition area to another. The largest of such gantry cranes are primarily located dockside in shipping ports around the world as well as in railroad yards. Quay cranes generally have either a horizontal sliding boom or a cantilever boom, the latter of which can usually be raised by rotating it around its inboard end. Long span yard and quay cranes are typically supported by vertical structures located inboard from the ends of the crane gantry on rail mounted wheels. The present invention can be utilized with any of these basic types of crane designs and operations.
Reference is made to FIG. 2 of the drawings which illustrate a typical cantilever boom type quay crane 11 having a buffer crane 25 of the present invention positioned thereunder. The quay crane cantilevered rotatable boom 27 is supported by the crane superstructure 29 mounted on crane truck wheels 31 which run on dock rails which are disposed parallel to the edge 13 of the harbor dock. The crane superstructure supports a horizontal gantry 33 disposed generally mid-height thereon at an elevated location above the cargo container pickup and deposition areas 35. The gantry is supported from below by the main legs of the superstructure.
In the cantilevered rotatable boom design for quay cranes, sheaves are disposed at the pinnacle 37 of the superstructure of the crane to guide wire rope reeving 39 which is used to lift the outboard or cantilevered end of the boom to the upright raised stowed position. The wire rope reeving raises the cantilevered boom by rotating it about its hinge point 43 at its inboard end proximate to the superstructure.
While, in most typical dockside applications, the gantry of a cargo container handling quay crane is a slidable or a raisable canfilevered boom extending from a crane superstructure to project over a ship, other types of large gantry yard cranes supported at both ends are located in large cargo container storage or transfer areas. All of these cranes are similar to the gantry type crane of FIG. 2 in that they employ a movable trolley 45, usually with a suspended operator""s cab 47, which shuttles along the gantry 33 and boom 27 suspending a cargo container lifting spreader 49. The spreader can be raised or lowered from the crane gantry by the operator and engages from above the top of cargo containers 17. The containers are carried by a transporter 21 or are stacked on the dock or shipboard to permit them to be lifted by the trolley for horizontal transport. During loading, the containers are lifted from the transporter and are moved outboard along the gantry to where they are lowered into the cells 51 in a cargo container transport ship. During unloading, the containers are lifted from the cells and moved from shipboard to shore where they are lowered onto the transporters.
The cargo container lift trolley 45, mounted on rails on the crane gantry sections 27, 33, can traverse from one end of the gantry to the other with a suspended container. The cargo container lifting spreader 49 is suspended from the trolley by fleet through wire rope reeving through a detachable headblock which carries the wire rope suspension sheaves. Different or variable length spreaders can be secured to the headblock to accommodate correspondingly different size containers.
There are two highly interdependent berthing sub-operations: (1) quay crane handling; and (2) transport vehicle movements between the crane and the stacking yard. A delay in one of those sub-operations causes the other to pause and idle which reduces the overall productivity of the entire system. Several factors can cause delays in the two berthing sub-operations including: (1) unsteady or irregular quay crane operations; (2) the time required for effecting interbox connector (IBC) installation and removal processes; (3) delays in stacking yard operations that delay throughput of transport vehicles; (4) the time required for quay cranes performing alignment of containers with transport chassis; (5) congestion of transport vehicles under quay cranes; and (6) various other factors such as machinery operator mistakes or inexperience.
Quay crane container handling rates are measured in cycle rates. Unsteady quay crane operations result because the cranes move containers different distances depending upon the location of the container on a ship varying the cycle rates. For example, as a quay crane loads or unloads each column of containers spaced across the beam of the ship, the hoist travels a longer distance outboard for each successive column of containers and lowers and hoists longer for each container located deeper in the stack. The increased traveling distance and stationary time for the hoist, for each successive container, adds to the container handling time and the resulting cycle time.
Unsteady quay crane operation, coupled with a constant number of transport vehicles allotted per crane, creates inefficiencies in the overall operation. When quay crane handling rates or cycle time are slow, transport vehicles must wait. In those instances where the quay crane handles containers fast and cycle time is short, and if the number of transport vehicles is insufficient for the cycle time, the quay crane must wait.
The interbox connector (IBC) installation and removal processes cause both quay cranes and transport vehicles to idle. IBCs are cone-shaped devices that lock stacked containers together on the ship. When quay cranes lift containers from the ship, the IBCs are still attached to the bottom of the container. Usually, the quay cranes must lower the container until it is a few feet above the port terminal dock level where a worker crew can reach underneath and remove the IBCs. The installation processes are just the reverse. The IBC operations cause a significant amount of quay crane and transport vehicle idle time to be induced into the system cycle time as well as exposing the workers to the possibility of injury from a swaying or dropped container or any other hazards associated with proximity to a lifted load and to continuous transport vehicle operations.
Delays in stacking yard operations also cause delays in the throughput of container transport vehicles. The vehicles load or unload containers at the stacking yard before returning to the cranes. Disruptions in the flow of transport vehicles to and from the quay crane loading area are caused by numerous factors such as driver inexperience and lack of familiarity with the apparatus and layout of the yard, as well as yard worker inexperience, which cause the delays in the stacking yard operations. If the disruptions are sufficiently severe, then the quay cranes must wait in idle for a transport vehicle to return.
Another source of delay results when quay cranes expend time aligning a suspended container with a container transport chassis during the container positioning and deposition process. The transport vehicles do not park in precise locations under the quay cranes. As a result, each container placement is in a slightly different location. This process of container lifting spreader alignment with the transport vehicle causes time-consuming delay in the quay cranes operation.
Finally, congestion of transport vehicles under the quay crane slows the rate at which containers are moved to and from the container ship. The situation is exacerbated when there are several cranes working in parallel and the ship carries refrigerated containers. The orientation of the refrigerated containers on the ship often requires that vehicle traffic flow two ways under the quay cranes in order to properly orient the containers on the transport chassis whereas unidirectional flow would create less congestion and danger to the dock workers.
The buffer crane operations and method of cargo container handling contemplated according to the present invention departs substantially from the conventional concepts, designs, and modes of quay crane operation taught by the prior art. In doing so, the present invention provides an apparatus and new method of sub-operation primarily developed for the purpose of improving the overall efficiency of berthing operations by reducing or eliminating the delay problems described above. It accomplishes the result in a different and improved manner and an overall new method of operation for the dockside handling of cargo containers.
The buffer crane of the present invention functions mainly by establishing a temporary storage or holding operation between the quay cranes and the transport vehicles which reduces the interdependence therebetween. The buffer operation in effect constitutes a container reservoir between two of the three berthing sub-operations quay crane handling and transport between the crane and the stacking yards. The temporary storage reservoir permits the quay crane to take or deposit containers even if no transporter is available, or conversely, for a transporter to extract a container, or deposit one in the reservoir, even if the quay crane is elsewhere. When one of the two sub-operations experiences a delay, the other sub-operation continues to work with the buffer operation while the delayed sub-operation resolves its problem.
In view of the foregoing known and obvious disadvantages inherent in the prior art types of quay cranes and berthing operations presently existing and utilized in seaports, the present invention provides a new crane construction and method of quay crane operation wherein the same can be utilized to improve the efficiency of cargo container ship berthing operations.
The general purpose of the present invention, which will be described hereafter in greater detail, is to provide a new crane apparatus and method for coordinated quay crane operation which has all of the advantages of the prior art mentioned above, as well as many novel features that result in new methods of berthing operations, which are not anticipated, rendered obvious, suggested, or even implied by any of the prior art of quay cranes and port berthing operations either alone or in any combination thereof.
The present invention is a buffer crane sub-operation for cargo container handling. It is a method for dockside buffer crane cargo container handling in combination with a quay crane. The steps comprise providing an independently movable platform having a multiplicity of cargo container landing positions disposed thereon and a dedicated crane engaged with the platform arranged to move or transfer containers between the platform and cargo container transporters located below the platform. The platform is positioned dockside under the quay crane and containers are moved by the quay crane between the landing positions on the platform and shipboard cells of a dockside berthed ship. Containers are also concurrently moved by the dedicated crane between the platform and cargo container transporters located below the platform.
These more important features of the method of the invention have been broadly outlined in order that the detailed description thereof which follows may be better understood and in order that the present contribution to an improvement in the art may be better appreciated. There are additional features of the method of the invention that will be described hereinafter and which will form supplemental subject matter of the claims appended hereto.
With respect to the claims hereof, and before describing at least one preferred embodiment of the invention in detail, it is to be understood that the invention is not to be limited in its application to the details of construction and to the arrangements of the components which are set forth in the following description or illustrated in the drawings. The invention is capable of being created in other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed here are for the purpose of description and should not be regarded as limiting.
As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other forms, structures, methods, and systems for carrying out the several purposes of the method of the present invention. It is important, therefore, that the claims be regarded as including such equivalent steps in the method in so far as they do not depart from the spirit and scope of the present invention.
Further, the purpose of the appended abstract is to enable the United States Patent and Trademark Office, and the public generally, and especially scientists, engineers and practitioners of the art who are not familiar with the patent and legal terms or phraseology, to determine quickly from cursory inspection the nature and essence of the technical disclosure of the application. The abstract is neither intended to define the invention of the specification, which is measured by the claims, nor is it intended to be limiting as to the scope of the invention in any way.
It is therefore an important object of the present invention to provide a new sub-operation for shipping port berthing operations which provides a buffer operation between quay crane operations and the container transport vehicles which service a stacking yard.
It is another object of the present invention to provide a buffer operation for quay crane berthing operations which provides an intermediary landing deck forming a cargo container reservoir between quay crane handling and dockside vehicle transport.
It is a further object of the present invention to provide a buffer crane operation to work in conjunction with a quay crane to increase the efficiency of berthing operations by reducing idle time of the quay crane and container transport vehicles.
It is still another object of the present invention to provide a new gantry frame apparatus for the sub-operation method having a protected service deck for port operators to perform IBC installation and removal operations while the containers are landed on the buffer crane whereby neither the quay crane nor the container transporters need to idle during those operations.
And it is yet a further object of the present invention to provide a supplemental independently movable gantry crane which can be supplied to presently existing quay cranes without additional tracks on the dockside and which provides a landing deck for containers and performs a supplemental buffer sub-operation to quay crane operations and permits IBC removal independent of quay crane involvement to increase the efficiency of berthing operations by reducing the quay crane cargo container handling cycle times.